Coevolution of ectomycorrhizal fungi and angiosperm at the late Cretaceous drives host-fungus co-diversification

This study aims to reveal the driver of explosive diversification in the fungal class Agaricomycetes, specifically to test the co-diversification scenario of ectomycorrhizal (EcM) fungi and angiosperm. Molecular phylogenetic trees of Agaricomycetes inferred from fragments of 89 single-copy genes indicate that the unidirectional evolution of EcM symbiosis occurred multiple times, dating from the Triassic to the early Paleogene. However, five analyses for estimating net diversification rates (speciation rates minus extinction rates) suggest that the explosive diversification occurred only at the stem of EcM fungal clades diverging at the late Cretaceous, coinciding with the rapid diversification of EcM angiosperm. The present findings suggest that the coevolution between EcM fungi and angiosperm at the late Cretaceous is responsible for the host-fungus co-diversification.